They warn the database amounts to an unwarranted intrusion into family life.

While they believe it will unfairly demonise up to four million youngsters who have ever been in contact with official bodies.

The government is proposing that separate databases, which currently exist on all 11 million children under the age of 18, should be linked together.

This will involve spending some £200 million on a computer child index which will be run by the Department for Education.

Up to 400,000 civil servants - including teachers, doctors, health visitors and social workers - will have access to the youngsters' records.

It is this sharing of information that a study group commissioned by the government's Information Commissioner is particularly worried about.

They warn: "The systems will intrude so much into privacy and family life that they will violate data protection law and human rights law.

"Families’ privacy and autonomy will be corroded as the government puts them under surveillance. The new policy will treat all parents as if they

cannot be trusted to bring up their children."

The damning report, titled: 'Children's Databases: Safety and Privacy', was compiled by a group of experts attached to the Foundation for Information Policy Research.

They warn: "The government hopes that sharing information from health, education, social care and youth justice systems will enable it to predict which children will become criminals.

"But predictions can be highly fallible, and labelling children can stigmatise them. Children ‘fingered’ by the computer as ‘bad’ may find that their teachers have lower expectations, while the police may be more likely to treat them as suspects rather than witnesses."

And they add: "Children will be bullied into providing intrusive data on themselves, their parents and friends without proper safeguards, and into giving their ‘consent’ to widespread data sharing without involvement of their parents, in contravention of the law."

The conclusions are highly embarrassing for the prime minister, who has seized on tackling problem children as a legacy issue.

In September, Tony Blair unveiled a provocative campaign to crack down on future problem children.

At the time, he said: "If we are not prepared to predict and intervene far more early, children are going to grow up in families that we know perfectly well are completely dysfunctional.

"The kids a few years down the line are going to be a menace to society and actually a threat to themselves."

The new database is central to the aim of identifying problem children and families.

There are suggestions that the Information Commissioner was originally due to publish the critical study at around the same time Mr Blair made his speech.

If that had happened, it would have provided a powerful challenge to the prime minister's plans.

Even yesterday, the publication of the study was downplayed. A press release was not issued by the Commissioner until late in the afternoon, while it only made a passing reference to the critical study.

The authors of the study are concerned that the new system will drag resources and focus away from protecting some 50,000 children who are considered to be at serious risk of abuse.

One, Dr Eileen Munro, of the London School of Economics said: 'When dealing with child abuse, we do need to override privacy.

"But the new policy extends this level of intrusion into families that are not even suspected of abusing their children, and to all concerns about children’s development.

"It will also over-stretch scarce resources, damage parents’ confidence and divert services from focussing on real cases of abuse."

Professor Douwe Korff, of London Metropolitan University, added: 'The proposed surveillance system is contrary to the basic principles of data protection and human rights law.

"It replaces professional discretion with computerised assessments of human behaviour that are inherently fallible.

"The system violates private and family life and intrudes on children’s rights without justification."

Professor Ross Anderson, of Cambridge University, said: "On the one hand this new database will be creating a 'big brother' surveillance system for children.

"Separately, it also risks stigmatising many children, leading to discrimination. Youngsters who might have come into contact with social workers through perfectly innocent reasons, perhaps because of a disability, might have a question mark against their name."

The Information Commissioner's office said yesterday that while it funded the research, the views were those of the authors. It denied that it had been leant on by the government to delay or downplay its publication.

Assistant commissioner, Jonathan Bamford, confirmed there are concerns about the level of information held about children on official databases. He said the organisation plans to issue a code of practice on the issue.

"There has been a substantial growth in the information held about children and this is something we need to look at carefully. Just because technology means that things can be done with personal information, it does not always follow that they should be done," he said.

"Public trust and confidence will be lost if there is excessive unwarranted intrusion into family life or if some of the issues that have been identified actually materialise."